PSI - Issue 13

Kai Suzuki et al. / Procedia Structural Integrity 13 (2018) 1065–1070 Kai Suzuki et al. / Structural Integrity Procedia 00 (2018) 000 – 000

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Conclusions

We have investigated the growth behavior of microstructurally small cracks in an equiatomic Fe-20Cr-20Ni-20Mn 20Co HEA and compared it with that in an Fe-18Cr-14Ni alloy (LEA) that shows a relatively low configurational entropy. The obtained results and insights are as follows: (1) The fatigue limit of the HEA was higher than that of the LEA because of the solid solution strengthening. (2) The scatter in crack growth rates of the HEA was larger than of the LEA. In addition, it remained even after its propagation to a length of 700 μm. The cause of the scatter was the temporal non-propagation or deceleration of the fatigue cracks in the HEA. (3) The fatigue crack in the HEA was highly deflected when compared with that in the LEA. The crack deflection was attributed to the crack growth along the slip plane. This work was financially supported by JSPS KAKENHI (JP16H06365 and JP17H04956), and the support is greatly appreciated. References Zhang, Y., Zuo, T. T., Tang, Z., Gao, M. C., Dahmen, K. A., Liaw, P. K., & Lu, Z. P. (2014). Microstructures and properties of high-entropy alloys. Progress in Materials Science, 61, 1-93. Cantor, B., Chang, I. T. H., Knight, P., & Vincent, A. J. B. (2004). Microstructural development in equiatomic multicomponent alloys. Materials Science and Engineering: A, 375, 213-218. Abbaschian, R., & Reed-Hill, R. E. (2008). Physical metallurgy principles. Cengage Learning., pp.261-286. Gludovatz, B., Hohenwarter, A., Catoor, D., Chang, E. H., George, E. P., & Ritchie, R. O. (2014). A fracture-resistant high-entropy alloy for cryogenic applications. Science, 345(6201), 1153-1158. Otto, F., Dlouhý, A., Somsen, C., Bei, H., Eggeler, G., & George, E. P. (2013). The influences of temperature and microstructure on the tensile properties of a CoCrFeMnNi high-entropy alloy. Acta Materialia, 61(15), 5743-5755. Thurston, K. V., Gludovatz, B., Hohenwarter, A., Laplanche, G., George, E. P., & Ritchie, R. O. (2017). Effect of temperature on the fatigue-crack growth behavior of the high-entropy alloy CrMnFeCoNi. Intermetallics, 88, 65-72. Zhang, Z., Mao, M. M., Wang, J., Gludovatz, B., Zhang, Z., Mao, S. X., ... & Ritchie, R. O. (2015). Nanoscale origins of the damage tolerance of the high-entropy alloy CrMnFeCoNi. Nature communications, 6, 10143. Goto, M. (1993). Scatter in small crack propagation and fatigue behaviour in carbon steels. Fatigue & Fracture of Engineering Materials & Structures, 16(8), 795-809. Ritchie, R. O., & Lankford, J. (1986). Small fatigue cracks: a statement of the problem and potential solutions. Materials Science and Engineering, 84, 11-16. Okamoto, N. L., Fujimoto, S., Kambara, Y., Kawamura, M., Chen, Z. M., Matsunoshita, H., ... & George, E. P. (2016). Size effect, critical resolved shear stress, stacking fault energy, and solid solution strengthening in the CrMnFeCoNi high-entropy alloy. Scientific reports, 6, 35863. Habib, K., Koyama, M., & Noguchi, H. (2017). Impact of Mn – C couples on fatigue crack growth in austenitic steels: Is the attractive atomic interaction negative or positive?. International Journal of Fatigue, 99, 1-12. Awatani, J., Katagiri, K., & Nakai, H. (1978). Dislocation structures around propagating fatigue cracks in iron. Metallurgical Transactions A, 9(1), 111-116. Suresh, S. (1998). Fatigue of materials. Cambridge university press. Ritchie, R. O. (1988). Mechanisms of fatigue crack propagation in metals, ceramics and composites: role of crack tip shielding. Materials Science and Engineering: A, 103(1), 15-28. Acknowledgements